When Sally Field talks about the "weight of the role" she has in Steven Spielberg's "Lincoln," she's not kidding. "I gained 25 pounds to play her," said the two-time Oscar winner. "And then I had to have knee surgery."

The actress didn't say whether surgery was worth it, but Fields' portrayal of Mary Todd Lincoln -- wife of the 16th president and one of the more problematic figures in the American political pantheon -- has become one of the more talked-about aspects of Spielberg's Civil War epic, which opens Nov. 16. Which is saying something, considering that Daniel Day Lewis' performance as the nation's secular saint is destined for canonization itself.

"We all have a preconceived idea of her," Field said of a woman viewed for the past 150 years as the Macbethian ball and chain burdening a man many consider our greatest president. "But I didn't want to start with a conclusion. I did my research as an actress; I pulled the pieces together, and created my own psychological profile of her. I think she's one of the most abused, misunderstood and underexamined women in our history."

Scripted by playwright Tony Kushner and based on Doris Kearns Goodwin's Pulitzer Prize-winning book "Team of Rivals," "Lincoln" is less a standard biopic than the story of the 13th Amendment. Having made his Emancipation Proclamation, Lincoln then needs it turned into cold, hard law. As the South's hopes are dimming, so are the amendment's chances -- without the war as leverage, there's no chance it will pass. Lincoln, a la Kushner-Goodwin, is a consummate politician, and though the film finds dignity in the man himself, it mines suspense out of the lowdown dirty political maneuvering of 1865 Washington.

Defender and tormentor

The humanity of the story, on the other hand, lies in the relationships between the Lincolns. Son Willie has died, and haunts his family's dreams. Young Tad (Gulliver McGrath) dresses as a soldier and makes the White House his playground. The older Robert (Joseph Gordon-Levitt) is itching to get into the war while he still has a chance. Mary, as played by Field (who won best actress Oscars for "Norma Rae" in 1980 and "Places in the Heart" in 1985), is an eloquent defender of her president and the cause; an occasional torment to her husband, and a woman who, under the surface, seems to be barely keeping it together.

"Well, I think that's the way it was," Field said. "She was highly emotional, she didn't like being in Washington, and her grief was extensive -- she'd lost two children. Almost as bad, she'd lost her position with Mr. Lincoln. She'd been his closest adviser and confidante, but she'd had moments of grave emotionality, and he was afraid of her: He didn't want her causing unrest at a time when he needed the White House calmer.

"At the same time, he was a depressive, with a huge dark side, and when he fell into a deep dark puddle, she was the one who dragged him out."

Depicted as a certifiable lunatic by Gore Vidal in his celebrated historical novel (and portrayed by Mary Tyler Moore in the much-respected 1988 TV miniseries "Gore Vidal's Lincoln"), Mary Todd came from a privileged background, a powerful Kentucky political family, was highly educated and highly astute. "They met at a party and danced together," said Kushner, "and afterwards she told her cousin, 'I just danced with the greatest man of his age and he's going to be president of the United States someday.'

"I think she's gotten a bum rap," Kusher added. "I don't think it's the case that she wasn't a person with bipolar features, but she functioned at a very high level. I'm impressed with her, and what Sally does is just astonishing."

Field seems to harbor genuine affection for a woman who was maligned in her day, and continues to be a kind of political whipping girlok. But she was more than that, Field said. "Yes, she predicted Lincoln's ascension the first time she met him. But she could be funny, too. It's a famous story, but they met at a party and danced and Lincoln later said, 'I wanted to dance with Mary so badly' and Mary said, 'And he did.' "

If "Lincoln" seems to have given work to every middle-age white male actor in Hollywood, that's probably close to the case. "We wanted to make a drama in which we accurately depicted the terms Lincoln was contending with," said Kushner. "They were in a slightly claustrophobic city, surrounded by the South, and in an environment of decision-making that had everything to do with white voters, white politicians and white administrators. We had to be honest about it."

All the more reason Field's work seems extraordinary, rising out of the crowd of grisly faces attached to the likes of Tommy Lee Jones (Thaddeus Stevens), Jared Harris (U.S. Grant) and Bruce McGill (Edwin Stanton). Field may hold a relatively small role in the great scheme of "Lincoln," but she's like a political wife -- her influence is not to be underestimated.

The 16th president and his wife have been portrayed by a lot of other performers, distinguished and otherwise -- including Benjamin Walker in this year's horror farce "Abraham Lincoln: Vampire Hunter." Here are a few of the other notable appearances on-screen by Honest Abe and his bride.

ABE LINCOLN IN ILLINOIS (1940) -- The usually austere/ severe Raymond Massey serves up a generous dose of cracker-barrel Lincoln in this boilerplate Hollywood biography, the kind someone felt had to be made. (Massey also played Lincoln in 1962's "How the West Was Won.") The masterpiece of casting, though, is Ruth Gordon (think "Rosemary's Baby") as Mary Todd Lincoln.

YOUNG MR. LINCOLN (1939) -- Abe was young and so was Henry Fonda, who embodied a wise-beyond-his-years Springfield lawyer saving two brothers from the noose, in this slightly fictionalized John Ford classic. Mary? She was played by onetime big-band singer Marjorie Weaver, who retired from the movies in 1945.

LINCOLN (1988) -- TV miniseries based on the celebrated Gore Vidal novel stars Sam Waterston (affecting the same slightly high-pitched voice Daniel Day-Lewis uses in the new "Lincoln") as the president and, as MTL, none other than MTM (Mary Tyler Moore). Well-done television for its day, although historians will forever be taking potshots at Vidal's casual way with history.

STAR TREK (1969) -- Actor Lee Bergere played Abe in the episode titled "The Savage Curtain," Lincoln having been one of Capt. James T. Kirk's boyhood heroes, way back in the 23rd century.

GENERAL ELECTRIC THEATER (1955) -- In an episode titled "Love Is Eternal," Richard Boone ("Have Gun Will Travel") played the president, which seems like a strange casting choice. Stranger still was the casting of Teresa Wright -- who played classic American sweethearts in films like "Shadow of a Doubt," "Pride of the Yankees" and "The Best Years of Our Lives" -- as the unpredictable Mrs. L.